Sorry to bother you again, and I'm really trying,but I tried using all your settings for lineart and lowered opacity of my sketch, however the lineart look INVISBLE to me, like a thin string and hardly visible. (1px.) So I use 20px and you can see it more? (Using A4 size) . I also get the feeling that my lineart looks worse than my own sketch. So most of the time, I give up on lineart and use the sketch with a few cleanups. Any advice to what to do or should I change something?

oh it depends of the size of your drawing inside your canva. if it's A4 with just a headshot that takes all the page, of course, 20px is okay, if it's a fullscenery with tinny details, 2 or 3 px will be better. just use what you're the most comfortable with. personally i rarely look at my brush size anymore ^^

for the clean linearts, i have no idea, if you make clean strokes, then it's fine, if your sketches are clean enough, then keep it (i do that too sometimes)

oh i don't have the exact ones anymore, the Sai i used to make this tutorial wasn't the official version, now i have the official one and didn't re make those brushes, but you can make a similar one in 30s (if you have the brush set, idk where i got them, probably here on DA). just with the brush shape : "rough round 3" [link]